Telephonic instrument



June 30,1931. Q w, p, s'ru z 1,812,571

7 TELEPHONIC INSTRUMENT 7 Filed May 9. 1928 2 Sheets-Sheet 1 f VENTOR.

(\ ATTORNEY,

June so, 1931. w P, STUNZ 1,812,571

TELEPHONIC INSTRUMENT Filed May 9. 1928 2 Sheets-Sheet 2 A TTORNE Y.

Patented June 30, 1931 UNITED A ENT orrlca WILLIAM sm'u isrz or LAnsnow-nn; MARYLAND, Assronon rose-rm nnrosl'r nn riws'rg QQM-IP'ANY or BALTIMQBE, n oonronarron on MARYLAND LE ONE Application filed May 9',

My invention relates to loud speaking sound transmitting instruments and has for ume and distinctness of sound waves car ried toa receiver from a transmitter or other source.

Also to provide a mechanism which will automatically compensate for difference or change: oi amplitude.

Also further'to provide an extremely sensitive loud speaking instrument in which the (li'aphragmis: maintained in its normal float:

ing' or balanced position through the medium of lts cush on gaskets, rocking lever armaturesand energy or its permanent horseshoe v magnets;

In rece vers of this general typehereto j fore made which, embody a diaplrragm permanent magnet, an electr c-magnet; and an arnr or lever of the armature operating upon the diapl i'ragin with an air "space be-i tween the armature and core ofthe eiectromagnet, and wherein the resiliency of the tended tobalance the diaphragm against the pull of the permanent magnet'verygood results were obtainable up to a given amplitude but when a greater amplitude was desirable diitlfi'culties were encountered in that the two foroesgthat is, the resiliency of the diaphragm and? the p anar the permanent magnet failed to'reactorcompress with the same pressure ratio and consequently the instrument failed togivefully satisfactoryresults underagreater amplitu de of movement. The difficulties are overcome under the resent invention; wherein the magnetic pul= of the permanent magnet on the diaphragm held betweenthe rtrbb'er rings or gaskets is'balanced so that the diaphragm is responsive in bothdirections of movement under practically the same pressure'rati'o, thereby obtaining greater amplitude of movement with greater volume and strength of sound waves and better quality in tone and cl earness of delivery. To" accomplish the foregoing, the invention comprises certain new and novel improve ments hereinafter particularly described and clearly defined by the appended claims; ref

diaphragm audits elastic or cushioned. scat INSTRUMENT 1928; Serial No. 276,361.

erence beinghad to theaccompanying draw ings forming a parthereof, and inwh-ich,

Figure 1' is a plan View showing one form of an instrument embodying the invention, the housing being shown in section;

Figure 2 is a sectional view taken on'line 2 2 of Fig. 1*, looking in direction or"- the arrows. V

Figure 3 is a sectional view taken onl-ine 3-3 of Fig. 2 lool'ringin the direction ofthe arrows, and a Figure 4 is an end elevation of thedevice In the drawings, the numeral 1 designates a housing in which may be secured a basemember'Q having a central opening 2a. pro.- vided with flange 2b which with. a plate 5 is adapted to iiornr an annular recess 20? wherein the diaphragInB, having a rubber cushioning ring eton each sideth-ereof, is

clamped, (see Fig.7 3).: The: proper resilency of the cushioning effect upon the diaphr'agm 3 may be had by adj ustingth e nuts 7 upon the su'pporting postsi 6, 6a and 6b;

The'plate 5 has an extending tube adapted to receive a sound distributor, or lioud speaker horn (not shown)". V

The supporting'postfi extends some distance from the base member 2 andi hasssecured thereto, a bracket member 8-,- having oppositely disposed arms 9 to which arose curely fixed the permanent horseshoe magnets 10 and 11. One arm of each permanent magnet is slightly longer than its mate,

and to the ends oi? said long arms are fas tened by screws 10a and lla,-the pole plates 10?) and 11b, providedwithreduced portio-ris to form cores 10c and 110, upon which are mounted the induction coils-10d and 11d; and iorming twoelectro-magnets.

The pole pieces or cores 100 and 110 of the induction coils are shown 'te-rminatingatf a point below-the plane surfaces IOeand li e of the short arms 10f andllf of the magnets 10 and 'll to provide air gaps 17 and 17a between the cores and armatures oi the cores, as

' illustrated; but the air gaps may be otherwi-seformed, for instance,the armatures may be set at an inclination to a vertical plane passing through the plane-surfaces lOe and 116 ofthe short arms 1'07 and 11f oi the permanent magnets whereby the inner or rear edges of the armatures contacting with the short arms will constitute a knife-edge hearing on the short arms, and which is an obvious change to the skilled in the art to form the air gaps.

The inner edge of the flat surface of each armature 12 and 13 overlaps the permanent magnets and 11, respectively, sufliciently to form a proper fulcrum thereon, as at 126 and 13?), upon the outer edges of the short arms 10; and 11 of the permanent magnets, and are magnetically held to the surfaces 106 and 116 of the permanent magnets 10 and 11, as shown (Figs. 2 and 4). The armatures 12 and 13, have inwardly extending levers 12a and 13a, respectively, whose ends terminate at a point approximately over the center of the diaphragm 3.

The diaphragm 3 has secured thereto, centrally, and extending at right angles therefrom, a stem or plunger rod 14, preferably a thin flat strip of aluminum or other suitable material (see Figs. 3 and 4). This stem 14 is provided with slots 15 and 16 which are properly spaced from each other; said slots 15 and 16 being adapted to receive and engage the inner notched ends of the armature levers 12a and 13a. It will be seen when the levers 12a and 1311 are pulled towards each other and their ends engaged in the slots 15 and 16, that positive air spaces as at 17 and 17a are formed between the under or inner surface of the armatures 12 and 13, and the ends of the cores 10c and 110 of the eleetro-magnets. In making assemblage of the parts, by manipulating the supporting posts 6, 6a and 6b, the permanent magnets may be moved slightly to or fromthe base member 2 until the air gaps or spaces 17 and 17 a are equal; the nuts on the said posts are then set, a magnetic balance of the armature levers and cushioned diaphragm having been thereby established. If at any time, after the parts'have been assembled, it is desired to change or vary the air space between the two armatures and the pole-pieces of the electro-magnets, it can be effected by adjustment on post 6. Provision for this is made by making the underface of the lateral arms 9 of member 8 convex as shown in an exaggerated degree at 9a in Figs. 1 and 2 of the drawing. This convexity admits of a suflicient degree of rocking or flexibility at the union or joint between the arms 9 of the member 8 and the two permanent magnets which are attached by the bolts shown to the extended arms of memher 8.

If it be desired to change the air gap between only one of the armatures and its companion pole-piece, the adjustment is effected on post Go or 6?), as the case may be, so that an individual adjustment of the air gap of the particular unit desired is obtained without changing the air gap of the other individual unit, the convex face of the arm to which is attached the permanent magnet of the individual unit in which adjustment is being made providing for the strain on the joint or union of that particularly magnet without affecting the magnet of the other unit in which adjustment is not desider. It will thus be observed that provision is made for simultaneous adjustment of the air gaps of both armatures, and also for adjustment of the air gap of one individual unit independent of the other unit.

The balancing of the movable parts leaves the diaphragm free to handle the vibrations set up by the fluctuation of the sound wave currents passing through the induction coils 10d and 1141, thus providing a sensitive mechanism which will operate smoothly, quietly, and automatically adapt itself to volumes of various degrees of strength, and greater variations in amplitude. The electro-magnets 10d and 11d (see Figs. 1 and 2), are similarly wound and connected to the source of electric energy, either in series or parallel, but

with one connected in the opposite polarity to the other, that is, in one electro-magnet the current enters by the inside wire and passes out by the outside wire, and in the other enters by the outside wire and leaves by the inside wire, whereby the two units act in unison and in the same direction on the diaphragm. For illustration, the vibrating current entering the magnet 10d by the inside wire 1072 passes out by the outside wire 10a, while the current which enters the electro-magnet 11d by the outside wire 11h, passes out by the inside wire 112'; this arrangement increases the pull of one unit While decreasing the pull of the other.

The shorter arm of each permanent magnet is shown as having its end on an oblique angle, or diagonally. This permits the armatures 12 and 13 to be set or mounted diago nally on the pole piece of the permanent magnet so as to be practically fulcrumed along the diagonal edge of the pole of the magnet to conform to the diagonal positioning of the arms or levers which converge towards the rod or stem which connects them to the center of the diaphragm 3, and thus the armatures have a substantially uniform lap and even fulcrum on the pole pieces of the permanent magnets, as illustrated in Fig. 2 of the drawing.

I have illustrated and described my invention in the preferred form, and have given the preferred details of construction, but changes may be made therein and be within the scope of the invention.

Having described my invention, and set forth its merits, what I claim is 1. In a telephonic instrument, a vibratable diaphragm from which wave producing vibrations are transmitted, a plurality of armatures each fulcrumed on a permanent mag- III) net, lever-arms extending from said armatures and having their free ends connected with the vibratable diaphragm to exert a pull in opposite directions thereon for bal ancing the diaphragm, and electro-magnets having their cores spaced by an air gap from the magnetically fulcrumed armatures, the windings of one electro-magnet being connected in opposite polarity to the other for action in unison and in the same direction on the diaphragm.

2. In a telephonic instrument, a vibratable diaphragm from which wave producing vibrations are transmitted, a plurality of permanent magnets, an armature fulcrumed on one pole of each magnet andprovided with a laterally extending lever, means connecting the free ends of both levers with the diaphragm, the armature and lever of one magnet lying in a difi'erent plane from the other to cause the levers to exert a pull in opposite directions for balancing the diaphragm.

-3. In a telephonic instrument, a vibratable diaphragm from which wave producing vi- 7 brations are transmitted, a plurality of permanent magnets, each having one arm shorter than the other and positioned with the short arm of one opposite the long arm of the other, and the ends of the short arms defining an oblique line, electromagnets supported from the long arms ofthe permanent magnets, armatures fulcrumedon the short arms of the permanent magnets along the oblique line thereof, and provided with levers i extending towards the central line of the diaphragm, the armatures being spaced from the cores of the electro-magnets, and means connecting the free ends of the levers with the central'portion of the diaphragm, the diaphragm being balanced in its vibrations by counter-pressure transmitted through the levers of the armatures actuated by the elec tro-magnets.

In testimony whereof I affix my signature.

WILLIAM P. STUNZ.

CERTIFICATE OF, CORRECTION Patent No. 1, 812, 571. Granted June 30, 1931, to

WILLIAM, P. STUNZ.

It is hereby certified that the above numbered patent was erroneously issued te "Safe Depesit and Trust Company of Baltimore, a Corporation of Maryland", as assignee, whereas said patent should have been issued to Safe Deposit and Trust Company of Baltimore, a Corporation of Maryland, as trustee under the will of George R. Webb, as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this, 11th day of August, A. D. 1931.

Wm, A. Kinnan, I (Seal) Acting Commissioner of Patents. 

